CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating activities:
Net income	$ 13,151	$ 22,482
Adjustments to reconcile net income to cash provided by operating activities:
Excess tax benefits from exercise or vesting of equity awards	(3,754)	(2,670)
Deferred income taxes	(1,845)	(537)
Depreciation and amortization	17,167	14,173
Stock-based compensation expense	13,721	9,713
Foreign currency transaction loss	2,527	1,666
Other non-cash items	939	2,736
Change in operating assets and liabilities:
Trade accounts receivable	59,049	42,611
Income taxes receivable and other current assets	(3,839)	2,599
Accounts payable and accrued expenses	(1,448)	(5,762)
Deferred revenue	4,287	(3,836)
Other long-term assets and liabilities	(1,688)	260
Cash provided by operating activities	98,267	83,435
Investing activities:
Purchase of marketable securities	(36,232)	(56,645)
Matured and called marketable securities	22,156	21,129
Payments for acquisitions, net of cash acquired	(2,600)
Investment in property and equipment	(5,809)	(4,158)
Cash used in investing activities	(22,485)	(39,674)
Financing activities:
Issuance of common stock for share-based compensation plans	629	970
Excess tax benefits from exercise or vesting of equity awards	3,754	2,670
Dividend payments to shareholders	(4,581)	(2,281)
Common stock repurchases for tax withholdings for net settlement of equity awards	(4,939)	(4,123)
Common stock repurchases under share repurchase programs	(12,266)	(9,178)
Cash used in financing activities	(17,403)	(11,942)
Effect of exchange rate on cash and cash equivalents	(2,065)	(517)
Net increase in cash and cash equivalents	56,314	31,302
Cash and cash equivalents, beginning of period	80,231	77,525
Cash and cash equivalents, end of period	$ 136,545	$ 108,827